The present invention relates to a machine for simultaneously manufacturing two continuous cigarette rods.
Machines of the aforementioned type are known to feature a carding unit consisting of a number of carding rollers and designed to produce, at the output, a stream of tobacco particles substantially equal in width to the length of the carding rollers.
As described in U.S. Pat. No. 4,372,326 filed by the present Applicant, G.D. S.p.A., said stream of tobacco is divided equally into two parts by a dividing device, so as to form two streams of tobacco particles which are fed along respective upflow channels closed off at the top by respective suction conveyors.
Each suction conveyor collects the respective tobacco particles in known manner, and feeds them, in the form of a continuous stream, on to a paper strip.
To be more exact, the stream of tobacco from the carding unit comes out inside a duct located at the bottom of an upflow duct, which forks at the top end to form two side by side upflow channels arranged substantially in the form of a V and crosswise in relation to the traveling direction of the suction conveyors.
Said channels are separated by a dividing wall comprising a wedge-shaped bottom portion and arranged with its vertex facing the top end of the upflow duct.
Said wedge-shaped bottom portion usually presents mechanical or pneumatic dividing and regulating means for ensuring the tobacco stream is divided into two substantially equal parts.
A major drawback of the above dividing device is that it limits the output speed of the cigarette manufacturing machine, on account of the bottlenecks formed by the channel inlets, which clog easily if tobacco is fed too forcefully up the duct.
Another drawback of the above device is its complex design, by virtue of featuring said flow regulating means, which means comprise actuating means for adjusting the inclination of the wedge-shaped tip of the dividing wall, and so increasing one tobacco stream at the expense of the other.
Yet a further drawback of the above device is that the dividing wall limits access inside at least one of the two channels, thus making routine cleaning and maintenance of the channels extremely difficult.